Latent hardener, manufacturing method for latent hardener, and adhesive

Abstract

There is provided an adhesive which hardens under the condition of low temperature within short time and has a high preserving property. The latent hardener of the present invention has hardener particles mainly comprising metal chelate and capsules covering the surface of the hardener particles where, in the surface part of the hardener particles, substituent of the resin component constituting the capsule is bonded to the metal chelate. Accordingly, mechanical strength of the capsule is high whereby the capsule is not broken in a step of kneading the latent hardener with an epoxy resin.

What is claimed is:  
     
       1. A latent hardener comprising: 
       a hardener particle mainly including either or both of metal chelate and metal alcoholate; and  
       a capsule covering the surface of the hardener particle said capsule including a resin component having a substituent of either hydroxyl group or carboxyl group or having substituents of hydroxyl group and carboxyl group and;  
       wherein the substituent or substituents of the resin component couple with either or both of the metal chelate and the metal alcoholate on a surface of the hardener particle.  
     
     
       2. The latent hardener according to  claim 1 , wherein the metal chelate mainly comprises aluminum chelate. 
     
     
       3. The latent hardener according to  claim 1 , wherein the metal alcoholate mainly comprises aluminum alcoholate. 
     
     
       4. The latent hardener according to  claim 1 , wherein the resin component mainly comprises polyvinyl alcohol. 
     
     
       5. A method for preparing a latent hardener including a hardener particle and a capsule covering a surface of the hardener particle, comprising the steps of: 
       preparing a capsule material made of a resin component having a substituent of either hydroxyl group or carboxyl group or having substituents of hydroxyl group and carboxyl group and formed in a powder having a smaller average particle size than that of the hardener particle; and  
       forming a capsule by adhering the capsule material on the surface of the hardener particle melting the capsule material that the capsule material adheres to encapsulate the hardener particle.  
     
     
       6. The method for preparing latent hardener according to  claim 5 , wherein the step of the forming a capsule has a mixing step where the hardener particle and the capsule material are mixed so that the capsule material is adhered on the surface of the hardener particle and a stirring step where the hardener particles in a state of being adhered with the capsule material are stirred so that the capsule material is melted. 
     
     
       7. The method for preparing a latent hardener according to any of  claim 5  and  claim 6 , wherein the ratio of the average particle size of the hardener particle to the average particle size of the capsule material is 100:80 or more. 
     
     
       8. The method for preparing a latent hardener according to any of  claim 5  and  claim 6 , wherein the ratio of the average particle size of the hardener particle to the average particle size of the capsule material is 100:50 or more. 
     
     
       9. The method for preparing latent hardener according to  claim 5 , wherein, after the capsule is formed, the capsule and the hardener particle are heated. 
     
     
       10. An adhesive having a thermosetting resin, a silane coupling agent and a latent hardener mentioned in any of  claim 1  to  claim 4 .